Recently, video and/or audio stream transmission via a network such as an Internet protocol (IP) network has been possible as a result of remarkable development of communication technology. In the video and/or audio stream transmission via the network such as the IP network, it is possible to realize transmission of video streams and audio streams at a low cost as compared with television broadcasting.
However, in the video and/or audio stream transmission via the network, the transmission time from a transmission side to a reception side is significantly different depending on a used band, a network congestion state, and/or a network path difference. The transmission time also fluctuates depending on network jitter or the like. Because of fluctuation in the transmission time, the reception side may not synchronize and output a plurality of streams even when the transmission side synchronizes and transmits the plurality of streams.
Moreover, in the network transmission, if a plurality of streams is transmitted for one program and if two streams are generated from one program and transmitted using a redundant line, a function of synchronizing a plurality of streams is necessary in the reception side. The former is, for example, the transmission of videos obtained by imaging one subject using a plurality of cameras. If network transmission times of all streams are not identical, temporal incongruity is generated when the streams are switched on the reception side. The latter is, for example, a case in which network transmission of one program is performed using the redundant line, and working/protection switching of two streams is performed in the reception side. If delay times of the two streams are not equally synchronized, discontinuity occurs in the streams at the time of switching.
To solve these problems, a function of adjusting transmission delays of a plurality of streams of video, audio, or the like via the network is necessary. Thus, the transmission side transmits the plurality of streams to the network by attaching time codes thereto, and the reception side synchronizes the plurality of streams by adjusting the delays of the respective streams using the time codes (for example, see Patent Document 1).